This demo shows a self-developed game engine which is meant to be used in the context of installations and audio-visual performances. The player is supposed to explore different game worlds and interact freely with their environments and non-player-characters. Almost everything the player does has musical consequences. The game worlds are collages of well-known vintage video game genres, like platformer, dungeon crawler, NES 'Mode 7' or isometric pseudo 3D, creating bizarre and confusing scenarios. It is possible modify the game while it is running (e.g. spawning/ destroying/teleporting actors, changing the tile map, trigger events etc.). This adds a level of live coding to a musical performance where the programmer can act as a musical partner. While the game engine is written in C++, the game logic is scripted with Lua. All sound is done in Pure Data using a selfwritten emulator of the Roland D-110 sound module and various other synthesis and sampling techniques. Maps can be desgined with a custom level editor. game_over was developed within the artistic research project "GAPPP" at the Institute of Electronic Music in Graz, Austria and is founded by the "Österreichisches Wissenschaftsfonds" (project number AR364-G24).